Method of and apparatus for testing lubricating oils



Sept. 26, 1939. H. L. THWAITES 2,174,021

METHOD OF'AND APPARATUS FOR TESTING LUBRICATING' OILS Filed May 13, 1936 3 Sheets-Sheet 1 H. THWAITES 2,174,021

METHOD OF AND-APPARATUS FOR TESTING LUBRICATING OILS Sept. 26, 1939.

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MZWSW Patented Sept. 26, 1939 a This invention the testing of METHOD OF AND APPARATUS FOR TEST- IN G LUBRICATING OILS Herman L. Thwaites, Westfleld, N. 1., assignor to Standard Oil ration of Delaware Development Compa a corpo- Application May 13, 1936, Serial No. 79,483 4 Claims. (01. 73-51 deals with an apparatus for lubricating oils, and has for its object the manufacture of a simple and inexpensive appara tus and method for determining,

with reasonable accuracy, the utility of an oil for lubricating internal combustion engines.

This object is attained by the apparatus set forth in the a Figure l is a over which the diagrammatic ccompanying drawings in which cross-sectional view of the cone oil is passed, while Figure 2 is a view in partial cross-section of the cone assembly including the heating means and control In illustrating the echanism. Figure 3 is a graph correlation of results obtained with the present apparatus compared with actual engine test results.

Heretofore, i

n spite of the large number of lubricating oil testing apparatuses and methods,

the only way in which suitability of an oil for bustion engines was to in such engine one could determine-the lubricating internal comactually employ such 01] under controlled laboratory conditions, and examine both the used oil and the condition of the engine after the run. Such a procedure was recent years, a been developed erative Fuel Research) one-cylinder engine of definite specifications tion. This method is both costly and tedious. Within more standardized method has by the use of the C. F. R. (Coopand conditions of operaapproved procedure for the evaluation of motor oils, but of course,

of high initial well as the dur possesses the disadvantages and operating expense, as of the test. It is also subcost ation iect to the additional detriment of rapid wear of moving parts requiring frequent blank runs' on reference oils;

The apparatus prepared according to this invention gives results which approximate very closely the results obtained by the 'C. F. R. en-

gine.

Referring to the drawings, the most essential unit of the apparatus is a hollow inverted metallic cone l of circular cross section, having milled out in screw fashion on its inner periphcry a continuous circumferential groove 2. These grooves are inclined toward the outer portion of the cone so 011 around the without interru as to facilitate-circulation of the cone from the top to the bottom ption. The oil is allowed to flow beginning of the groove at the top of the cone 2 and is slowly )fat the botto 3 of the groove to the end therein of the cone 4, wherefrom the to a smooth finish with now considered as the most.

oil issues out of the cone through discharge tube 5.

This cone iron, although embodiment, the cone has a narrowing down over a distop of the threadsurface may be rubbed down sandpaper, emery cloth,

to the heater. ture is maintained constant by justable slide cury thermo-regulator IS The temperature at the inner surface of the cone is measured by thermocouple l6 and potentiometer IT. A graduated dropping funnel l8, containing the oil to be-tested is supported over the cone so as to slowly feed oil from the tip l9 to the first thread 2 on cone I. If desired a cover 2| may be provided for the cone I, which vided with openings adapted to permit the insertion into the interior of the cone of instruments l5 and I 6 or the like. After the oil completes its passage over the thread it emerges through outlet tube 5 into graduate 20.

The preferred-testv procedure is to allow a determined volume (say 60 cc.) of the oil to be tested to flow slowly over the thread surface of the cone, allowing a time of contact of about one minute between the heated metal surface and the oil. The total volume of 60 cc. of the oil is dropped during a period of 2 hours to obtain this rate. A temperature of 250 C. (482 F.) is most desirable although lower tempera- Ihe temperameans of ad- 'cover should be protures or those higher, e. g., 300 C. or even 350 C. may be used in some cases.

The cone is weighed before the test. After the fixed volume of the oil the quality of which is to be determined is run over the metal surface, the cone is washed with naphtha to remove adhering oil, dried, and the total deposit is obtained by the difference in weight. This value is generally reported in grams, the higher value showing a poorer oil. The same oil may be passed over the cone one, two, three or more times to give a better indication as to its stability upon repeated exposure on the heated cone. This may be accomplished mechanically or by the use of a recirculating pump.

The exceptionally good correlation of the re-' sults obtained by the apparatus and method disclosed herein with actual engine test results is shown in Figure 3. In the graph, the cone ratings (deposit in grams) of the various oils (denoted by the small circles) are plotted against .their demerit ratings after the second hour period on the C. F. R. engine. In the latter test, a definite quantity of lubricating oil is employed to lubricate a one-cylinder internal combustion engine at 390 F. jacket temperature. At the end of 15 hours, the engine parts such as the rings, grooves, piston surfaces, carbon deposits,

etc., are observed, and each part is rated, the total value being the demerit rating. The same oil is then replaced in the cleaned engine which isagain run for 15 hours under the same conditijons, this being a more severe test since the oil hasalready been subjected to a previous 15 hour period. The demerit rating is then obtained on the engine parts as above, and this is the value plotted as the abscissa in Figure 3, the lower demerit rating indicating a better oil for lubrication under such conditions. In view of the poor cor- ,relation of previous chemical tests with actual engine performance, the value of the test involved in the present invention is readily apparen Although this test is especially applicable toviscous hydrocarbon lubricating oils, it may bea likewise used to test other oils containing fatty compounds, blending agents, and the like.

An advantageous feature of the cone is its accessibility for cleaning ,and the ease in carrying out such operations, For instance, the thread groove and means surface may be washed .oil. with solvent and brush, or scraped off with emery cloth or sand- P p Although there have been shown and described specific embodiments of this invention, many modifications thereof are possible. The invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. Apparatus for determining the quality of lubricating oil used in an internal combustion engine comprising an inverted metal cone havin an inclined circumferential groove on its inner surface adapted to allow the oil to be tested to slowly flow on the top of said groove around the inner surface 'of'the cone and through an outlet at the bottom of said cone and means for heating said cone as hereinabove set forth.

2. Apparatus for determining the quality of lubricating oils for use in an internal combustion engine, comprising a jacket having a substantially frusto-conical' passageway extending along its vertical axis and a heating element disposed adjacent the walls of said passageway, an inverted metal cone, having an inclined circumferential groove on its inner surface, adapted to allow the'oil to be tested to slowly flow on top of said groove around the inner surface of the cone and through an-outlet at the bottom of said cone disposed in the passageway of said jacket with the outlet extendingbeyond the passageway, a cover for said cone, means for supplying oil to the for regulating the temperature within the cone extending through an opening in said cover.

3. Method of testing lubricating oils to determine their suitability for use in internal combustion engines, comprising passing a small stream of an oil to be tested over a confined path in a heated metal body, in the'presence of a material in a substantially gaseous form, washing said metal body to remove adhering oil and weighing the residue adhering to said surface,-to obtain an index of the quality of the oil.

4. A method of testing. lubricating oils according to claim 3, in which the oil is maintained in contact with the heated metal body for of at least oneminute.

HERMAN'L THWAITES.

a period 

